1. Field of the Invention
The present invention relates to a method for using Product R as hereinafter defined to treat patients infected with B19 parvovirus.
2. Description of the Related Art
Treatment of viral diseases in humans is a major focus of medical science. While some progress has been made, viral infections are still among the diseases most difficult to treat. Despite growing understanding of viral diseases along with improved techniques for detecting and treating them, few antiviral drugs have proved effective. Some viral diseases such as HIV are life threatening; others such as herpes simplex virus and influenza virus continue to cause severe problems. Further, new viral diseases constantly appear as an inevitable consequence of evolution. Thus, searching for a novel and effective way of treating viral diseases remains imperative and challenging.
Product R.sup.1 emerged as an antiviral product in the 1930's. While it was originally believed to be a product composed of peptone, peptides and nucleic acids (fully defined hereafter), the precise composition remains unidentified. Nevertheless, Product R has demonstrated an ability to inhibit rapidly the course of several viral diseases. It is nontoxic, miscible with tissue fluids and blood sera and free from anaphylactogenic properties.
 FNT 1. The agent is known under the trademark "Reticulose", a trademark of Advanced Viral Research Corp.
Despite these early promising clinical reports, systematic studies have rarely been performed to establish clinical utility. Optimum dosages of Product R for treating viral infections as indicated above have been poorly investigated. In fact, most of the clinical reports lacked necessary controls and statistically sufficient samples for evaluating the effectiveness of Product R. Note, two earlier publications challenged that Product R failed to demonstrated antiviral activity. In light of this controversy, the present status of the art of using Product R in treating viral infections remains questionable. Close examination of the development history of Product R reveals no meaningful pattern that could be followed to designate a treatment for a particular viral infection, for viruses causing those infections are extremely diversified in their genetic traits or/and pathogenesis. In addition, earlier clinical applications described Product R only as an agent to be administered alone. Product R has never been suggested to be applied in combination with other antiviral drugs; nor has Product R been administered for a period longer than about two months. Given the limits of prior art, developing new treatment strategies using Product R is desirable.
In developing an antiviral agent, it is well known that inhibitory activity of an antiviral agent against a particular virus cannot be equated with its inhibitory effect against another virus. For example, acyclovir has proved to be specifically effective against herpes simplex 1 and 2 but not against cytomegalovirus (CMV), even though both HSV and CMV belong to the same herpesvirus family, sharing certain genetic features. The specificity of acyclovir rests on the activity of the thymidine kinase gene unique to HSV 1 and 2, indicating that a distinctive feature of each individual virus forms a basis for developing an antiviral agent specifically against this very virus. In other words, treatment of a viral infection using a certain antiviral agent does not necessarily indicate that the same agent will produce the same effect when used for treating other viral infections. The genetic diversity of viruses further mandates that an attempt to be made to discern the effectiveness of a new application of an antiviral agent to a different virus.
An antiviral agent usually interacts with molecules involved in different stages of viral infections: in early events such as adsorption, penetration (internalization), and uncoating; in virus replication characteristic for each virus genome and components of the nucleoprotein complex; and in the chemistry of metabolic pathways. The best targets for inhibition by an antiviral agent are molecules serving a function unique to the virus, with no analogous counterpart in host cells. In order to identify the virus-specific molecule with which a putative antiviral agent interacts, it is important to characterize viruses in terms of particle and genome structure, as well as to define specific biochemical events that occur in infected cells. Although progress has been made in discovering molecules necessary for virus adsorption, replication and metabolism, current knowledge remains insufficient to explain many aspects of these events. Consequently, not every antiviral agent's function is fully defined in terms of its interaction with a target virus through one or a series of the indicated events; much less is understood where an antiviral agent is employed to treat a new viral infection, especially if the antiviral agent has been poorly characterized. Without the knowledge of a virus' genetic traits and the chemical properties of an antiviral agent, treatment of a viral infection becomes unpredictable.